Burner assembly



Jan. 20, 1959 A. J. NERAD 2,869,629

BURNER ASSEMBLY Filed Dec. 8, 1955 Inventor.-

A r7 thony d Ne rad,

/'-//'s Attorney.

BURNER ASSEMBLY Anthony Nerad, Alplaus, N. Y., assignor to GeneralElectric Company, a corporation of New York This invention relates toburner assemblies and more particularly to burner assemblies which areused in gas turbine combustors, ramjets, afterburners, and household oiland gas burners.

.Flame extinguishment is a serious problem in gas turbine, jet,vpropulsion, and domestic heating fields. A burner assembly whichproduces a stable flame is desirable to provide eflicient combustion andto prevent flame extinguishmentr Some present combustors use arapidlyburning fuel or an increased amount of fuel in the fuel-airmixture 'to stabilize the flame. However, such additional fuelconsumption creates a higher operating cost for the apparatus andrequires excessive storage ispace for the fuel. The invention of thepresent application provides a burner assembly which has flamestabilization of a high order with normal requirements of a conventionalliquid, gas or solid fuel.

Accordingly, it is an object of my invention to provide a new andimproved burner assembly.

It is another object of the invention to provide an improved burnerassembly which produces a stabilized flame without excessive fuelconsumption.

It is another object of the invention to provide an improved burnerassembly which can be used in gas turbine combustors, ramjets,afterburners, and household type oil and gas burners.

It is a further object of the invention to provide an improved burnerassembly in which a portion of the flame stream is returned mechanicallyto the flame base to produce stable combustion.

In carrying out my invention in one form, a pair of inwardly curvednumbers are positioned adjacent the outlet end of a fuel-air casing toproduce a direct mechanical return of a portion of the flame from a zoneof combustion to the flame base. Thus, thermal regeneration ofa highandcontrollable value is provided for high space rates of combustion.

These and various other objects, features and advantages of theinvention will be better understood from the following description takenin connection with the accompanying drawing in which:

Fig. 1 is a partial sectional view of a burner assembly which embodiesmy invention;

Fig. 2 is a front elevational view of the burner assembly shown in Fig.1; and

Fig. 3 is a partial sectional view of a modified burne assembly.

In Figs. 1 and 2 of the drawing, a burner assembly is shown whichcomprises a fuel tube 11 spaced coaxially within an outer air inletcasing 12. Tube 11 which is shown in the form of a cylinder has a closedoutlet end 13 with a central fuel aperture 14 therethrough. Thisarrangement is broadly descriptive of various forms of fuel nozzles.Casing 12 projects beyond closed end 13 to provide an air stream foratomization of fuel which is sprayed from aperture 14. Air and fuel aresupplied to their respective casing and tube from any suitable sources(not shown). A pair of radial the burning stream of fuel air mixture.

c 1 2,869,629 Patented Jan. 20, 1959 ly and axially extending inwardlycurved metallic members 15 with inturned lips 16 are positioned onopposite, outer surfaces of casing 12 adjacent the outlet end thereof oralternately may be formed from extensions of end portions of the casing12. The inwardly curving may be defined in one sense as a hook member ora volute curve which commences in a direction substantially parallel tothe longitudinal axis of the casing 12 and progresses in a generalradial and axial direction away from the fuel outlet end 13 with thesmooth volute curving inwardly toward the longitudinal axis of thecasing and terminating in an inturned lip surface facing outlet end 13to provide a stripping or peeling action of part of If it is desired,members 15 may be composed of a suitable refractory material. While apair of members 15 are shown in Fig. 1 of the drawing, it should beunderstood that a single member or a plurality of members could beemployed, and that such members may be axially extending without havingan increase in the radial dimension. These members may be curved flatstrips or have inner planar surfaces to peel a portion of the burningmixtureand guide or redirect this portion rearwardly to the fuel nozzleoutlet end 13. I have found that a space should be provided betweenadjacent membersfor side air flow to support combustion.

In operation of burner assembly 10, a liquid, gas or solid fuel isprovided from a source of supply (not shown) through tube 11 and sprayedfrom aperture14 into an air stream which is produced by tube 12.. Theatomized fuel-air mixture is ignited within the confines of members 15in any suitable manner to provide an initial flame stream which extendsbeyond members 15 as indicated by arrows 17 and engulfs lips 16. Aportion of the flame is peeled off by lips 16 and returned directly tothe base of the flame by members 15 .as indicated by arrows 18. Thismechanical return of a portion of the flame stream from a zone of hot,rapid combustion to the flame base stabilizes the initial flame.

stream through a mixing of hot combustion products to provide eflicientcombustion and to prevent flame extinguishment. I have discovered that asubstantial portion of the initial stream can be returned to the flamebase with an increased stabilization of high order.

In Fig. 3 of the drawing, a modified burner assembly 20 is shown whichcomprises a fuel tube 11 spaced c0- axially with an outer air inletcasing 12. Closed outlet end 13 of tube 11 has a central aperture 14therethrough. A pair of hollow, inwardly curved members 21 with inturnedlips 22 are positioned on opposite, outer surfaces of the outlet end ofcasing 12. The inner wall of each member 21 has a plurality of louvers23 with associated apertures 24 which are directed toward the outlet endof casing 12 to provide an additional fluid stream, such as, air forcombustion and cooling.

In the operation of burner assembly 21], the atomized fuel-air mixturefrom tube 11 and casing 12 is ignited to produce an initial flame streamwhich extends beyond members 21 as indicated by arrows 25. A portion ofthe flame is peeled off by lips 22 and returned to the flame base bymembers 21 as indicated by arrows 26. This mechanical return of aportion of the hot burning and burned combustion products to the flamebase stabilizes the initial flame stream. An air stream flows throughinlet 28 to each member 21 from a source of supply (not shown) asindicated by arrows 27 to cool the member during burner assemblyoperation. Air is discharged from members 21 through apertures 24 anddirected by louvers 23 in a vortical stream toward the casing outlet toprovide additional air for mixing with combustion products and theburning reactants.

As will be apparent to those skilled in the art, the

objects ofmy' invention are attained by" the use of a pair of inwardlycurved members which are positioned adjacent the outlet end of afuel-air casing to produce a direct mechanical return of a portion ofthe flame from a zone of combustion to the flame base to provide ahighly stabilized flame.

1While other modifications of this invention and variations of apparatuswhich may be employed within the scope of the invention have not beendescribed, the invention is intended to include all such as may beembraced within the following claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

l, A burner assembly comprising a hollow, substantially cylindricalcasing having an inlet and an outlet, a fuel tube spaced coaxiallywithin said cylindrical casing, a closed outlet end on said tube, saidclosed end having a central aperture therein and spaced inwardly fromthe outlet of said cylindrical casing whereby a fuel air stream isejected from said outlet for ignition thereof, a hollow strip memberpositioned adjacent the outlet of said cylinder to extend therefrom in ageneral radial and axial direction and curving inwardly toward thelongitudinal axis of said cylindrical casing to form a lip surfacefacing the outlet ofv said casing, said lip surface intercepting aportionof the burning fuel air mixture for redirection along the lipsurface to the casing outlet, said hollow .strip members defining an airpassage therein, and a plutially' cylindrical casing having an inlet andan outlet, a fuel tube spaced coaxially within said cylindrical casing,

a closed outlet end on said tube, said closed end having a centralaperture therein and spaced inwardly from the outlet end of saidcylindrical casing to provide a fuel air stream ejecting from saidoutlet for ignition thereof, a

plurality of hollow relatively flat strip members adjacent the outletend on said cylindrical casing and positioned en the periphery thereofin opposite and species flit surface relation to eachother, the saidmembers extending from the said outlet in a generally radial and thatdirection and curving inwardly toward each other and the longitudinalaxis of said cylinder to provide a lip surface facing the casing outlet,said lip surface intercepting a portion of the burning fuel air mixturefor redirection along the lip surface toward th e casing outlet, thesaid members defining an internal air passage therein, and a pluralityof louvres on the said lip surface to provide a vortical air stream forthe redirected portion of the burning fuel air mixture; j v

3. A burner assembly comprising in combination a fuel nozzle to emit aspray of fuel, means supplying combustion air for mixture with the fuelspray for burning thereof, a hollow strip member, means supporting thehollow strip member adjacent the periphery of the nozzle at the outletthereof, said strip member extending from the outlet of said nozzle in agenerally radial and axial direction and curving inwardly toward thelongitudinal axis of said nozzle to form a lip surface'facing the outletof said nozzle, said lip surface intercepting a portion of the burriingfuel air mixture for redirection along the lip surface to the nozzleoutlet, said hollow strip member defining an inner air passage, and aplurality of louvres' 011 said lip surface to provide a vortical airstream for the redirected portion of the burning. fuel air mixture;

References Cited in the i116 of this atent,

UNITED STATE-S PATENTS

